1. Field of the Invention
This invention is generally related to water flow control systems, and more particularly, to a system and method for controlling the flow of water in a flush of a toilet.
2. General Background and State of the Art
Water flow systems include flush toilets, each of which includes a toilet tank, wherein a flush is created by a flush valve that opens and closes to release water from the tank to the bowl to create a flush. Flush valves are buoyant. Therefore, when a toilet is flushed, the flush valve floats and remains open for a fixed amount of time, until the water in the tank lowers to the point where the buoyant flush valve can no longer float, at which time the flush valve closes.
The most common toilet currently found in the home is a gravity flush tank type toilet. A tank style toilet includes a tank and a toilet bowl. The tank is initially filled through a fill valve. A buoyant flush valve is mounted in the bottom of the tank, which releases the water in the toilet tank to flush the toilet bowl. In addition, a siphon is molded into the bowl. As water enters the bowl, the extra water spills over the edge of the siphon tube and drains away into the sewer pipe. Water enters the bowl at a fast rate, causing the siphon tube to fill, whereupon the siphon flushes the fluid and any waste out of the bowl into the sewer pipe. The bowl is emptied, air enters the siphon tube, and the siphoning process stops. The toilet tank operates to supply a volume of water to the bowl at a sufficient rate to activate the siphon.
The flush valve is mounted in an opening and controls water flow between the tank and the bowl. The flush valve includes a valve seat and a flap lid. Most flush valves operate with a flap lid, also known as a flapper.
There are four common types of flush valves: a flap lid type, an actuator type, a cylinder type, which is also known as a Certain Flush valve or Mansfield valve, and a lift wire type. These four flush valve types, though appearing different in size and shape, all include a flush valve that floats in the open position.
A dual flush toilet has two different flush options for water conservation, a smaller water volume which is used for flushing liquid waste, and a larger water volume which is used for flushing solid waste. Currently, dual flush retrofit kits, for enabling two different flush cycles, have two different flush valves which open and close where water can exit, and two different flush levers, so that the user can select a large flush or a small flush. They require changing the flush lever and flush valve of an existing toilet. Installation of these dual flush retrofit kits typically requires disassembling the entire toilet, so that the flush valve and flush handle can be replaced.
Dual flush toilet specifications outlined by the Environmental Protection Agency for water conservation call for dual flush toilets to use less than a gallon (three liters) of water to flush liquid waste, and approximately one-point-six gallons (six liters) to flush solid waste, which equates to an effective flush volume of one-point-two-eight gallons.
The U.S. Congress mandated that all toilets sold in the U.S. as of Jan. 1, 1994 be Ultra-Low-Flush Toilets (ULFTs) having a maximum average flush volume not exceeding one-point-six gallons (six liters) per flush. The ULFTs are significantly more water efficient then the older toilets which used three-point-five, five, and seven gallons of water per flush.
When a dual flush retrofit kit is used with a ULFT toilet, it increases the amount of water used during a large flush. In particular, many ULFTs use a high water capacity tank, which holds three-point-five gallons, but use an early-closing flapper to achieve a one-point-six gallon flush volume. An early closing flapper has a reduced buoyancy which causes the flapper to close the flush valve before the tank is entirely evacuated of water. As a result, only a fraction of the water in the tank of ULFTs flows through the flush valve to the bowl before the flush valve closes. When a dual flush retrofit kits is installed in a ULFT that uses an early closing flapper, the result is that all three-point-five gallons of water in the tank are used during the full flush cycle. ULFTs are designed to only use one-point-six gallons per flush. However, water consumption can increase to three-point-five gallons per flush during the full flush cycle with dual flush retrofit kit.
Therefore, there has been identified a continuing need to provide system and methods for controlling the flow of water during the flushing of a toilet, to conserve water.